Exploring Customers’ Preferences for Online Games

Online content providers who use the Internet to distribute content experience an extremely competitive business environment. To survive in this environment, they have started charging a fee for the content that they provide. However, there have been very few success stories in commercializing online content. Although one of few success stories is the online game, it still has customers’ psychological resistance against paying a high fee for playing games. To pay back their high R&D or development costs quickly, many online game producers have a tendency to assign high prices to their online games. Without examining customers’ perceived prices for online games, many online game producers have tended to decide prices from their perspectives. Although many online game-related research works have focused on psychological and technical aspects, very few works have examined online gamers’ preferences carefully. This study aims at exploring online gamers’ preference by measuring their WTP (Willingness To Pay) for online games

BIOMECHANICAL ANALYSIS OF BACK-SOMERSAULT KICKS IN TAEKWONDO

This study was purposed to investigate biomechanical differences between best and worst trials in performing back-somersault kicks in Taekwondo. Six elite members of college Taekwondo demonstration team participated in this study and executed each ten trials of single back-somersault kick and double back-somersault kick, respectively. High speed motion capturing system collected positions of 21 markers on major anatomical locations to obtain motion data of full body segments. After post-processing procedure, results showed that the best trial of back-somersault kicks indicated longer preparation time (countermovement), larger range of motions of hip joint, and higher peak angular velocities of knee and hip joints prior to take-off than those of the worst trial. We concluded that athletes should avoid a quick countermovement before take-off, which induces insufficient strain energy of lower extremities and ground reaction impulse. Therefore, a sufficient time for muscle contractions are required to develop high power

Fabrication and characterization of silicon wire solar cells having ZnO nanorod antireflection coating on Al-doped ZnO seed layer

In this study, we have fabricated and characterized the silicon [Si] wire solar cells with conformal ZnO nanorod antireflection coating [ARC] grown on a Al-doped ZnO [AZO] seed layer. Vertically aligned Si wire arrays were fabricated by electrochemical etching and, the pn junction was prepared by spin-on dopant diffusion method. Hydrothermal growth of the ZnO nanorods was followed by AZO film deposition on high aspect ratio Si microwire arrays by atomic layer deposition [ALD]. The introduction of an ALD-deposited AZO film on Si wire arrays not only helps to create the ZnO nanorod arrays, but also has a strong impact on the reduction of surface recombination. The reflectance spectra show that ZnO nanorods were used as an efficient ARC to enhance light absorption by multiple scattering. Also, from the current-voltage results, we found that the combination of the AZO film and ZnO nanorods on Si wire solar cells leads to an increased power conversion efficiency by more than 27% compared to the cells without it. © 2012 Baek et al.1

Effect of preoperative statin therapy on myocardial protection and morbidity endpoints following off-pump coronary bypass surgery in patients with elevated C-reactive protein level

BACKGROUND: The aim of this study was to investigate the effects of preoperative statin therapy on myocardial protection and morbidity endpoints following off-pump coronary bypass graft surgery (OPCAB) in patients with elevated serum high-sensitivity C-reactive protein (hs-CRP) levels. METHODS: Of the 492 patients who underwent multivessel OPCAB from March 2007 to February 2009, the records of 144 patients whose baseline hs-CRP level > 2 mg/L were reviewed. According to the history of preoperative statin therapy for at least one week, patients were classified as either statin group or control group (72 subjects each). Preoperative and operative characteristics and postoperative data including troponin (Tn)-T level and major morbidity endpoints were obtained and compared. Major morbidity endpoints were defined as permanent stroke, renal dysfunction, hemostatic re-exploration, deep sternal wound infection, and the number of patients requiring prolonged ventilation. RESULTS: Preoperative and operative characteristics were similar between the two groups. There were no significant differences in the incidence of morbidity endpoints between the two groups, except for the number of patients requiring dialysis, which was significantly lower in the statin group (8 vs. 1, P = 0.033). Tn-T level at 24 h after surgery was also significantly lower in the statin group. CONCLUSIONS: In this study, we observed beneficial effects of preoperative statin therapy for at least one week in terms of less myocardial enzyme release and fewer patients requiring dialysis following OPCAB in patients whose preoperative hs-CRP was elevatedope

Visible emission from Ce-doped ZnO nanorods grown by hydrothermal method without a post thermal annealing process

Visible light-emitting Ce-doped ZnO nanorods [NRs] without a post thermal annealing process were grown by hydrothermal method on a Si (100) substrate at a low temperature of 90°C. The structural investigations of Ce-doped ZnO NRs showed that the Ce3+ ions were successfully incorporated into the ZnO lattice sites without forming unwanted Ce-related compounds or precipitates. The optical investigation by photoluminescence spectra shows that the doped Ce3+ ions in the ZnO NRs act as an efficient luminescence center at 540 nm which corresponds to the optical transition of 5d → 4f orbitals in the Ce3+ ions. The photoluminescence intensity of the Ce-doped ZnO NRs increased with the increasing content of the Ce-doping agent because the energy transfer of the excited electrons in ZnO to the Ce3+ ions would be enhanced by increased Ce3+ ions

A new classification system for bacterial Rieske non-heme iron aromatic ring-hydroxylating oxygenases

<p>Abstract</p> <p>Background</p> <p>Rieske non-heme iron aromatic ring-hydroxylating oxygenases (RHOs) are multi-component enzyme systems that are remarkably diverse in bacteria isolated from diverse habitats. Since the first classification in 1990, there has been a need to devise a new classification scheme for these enzymes because many RHOs have been discovered, which do not belong to any group in the previous classification. Here, we present a scheme for classification of RHOs reflecting new sequence information and interactions between RHO enzyme components.</p> <p>Result</p> <p>We have analyzed a total of 130 RHO enzymes in which 25 well-characterized RHO enzymes were used as standards to test our hypothesis for the proposed classification system. From the sequence analysis of electron transport chain (ETC) components of the standard RHOs, we extracted classification keys that reflect not only the phylogenetic affiliation within each component but also relationship among components. Oxygenase components of standard RHOs were phylogenetically classified into 10 groups with the classification keys derived from ETC components. This phylogenetic classification scheme was converted to a new systematic classification consisting of 5 distinct types. The new classification system was statistically examined to justify its stability. Type I represents two-component RHO systems that consist of an oxygenase and an FNR_C-type reductase. Type II contains other two-component RHO systems that consist of an oxygenase and an FNR_N-type reductase. Type III represents a group of three-component RHO systems that consist of an oxygenase, a [2Fe-2S]-type ferredoxin and an FNR_N-type reductase. Type IV represents another three-component systems that consist of oxygenase, [2Fe-2S]-type ferredoxin and GR-type reductase. Type V represents another different three-component systems that consist of an oxygenase, a [3Fe-4S]-type ferredoxin and a GR-type reductase.</p> <p>Conclusion</p> <p>The new classification system provides the following features. First, the new classification system analyzes RHO enzymes as a whole. RwithSecond, the new classification system is not static but responds dynamically to the growing pool of RHO enzymes. Third, our classification can be applied reliably to the classification of incomplete RHOs. Fourth, the classification has direct applicability to experimental work. Fifth, the system provides new insights into the evolution of RHO systems based on enzyme interaction.</p

Multi-Criteria Coordinated Electric Vehicle-Drone Hybrid Delivery Service Planning

According to recent works, a coordinated delivery strategy in which terrestrial and aerial electric vehicles work together effectively improves delivery throughput and energy efficiency. However, most research on logistics and transportation focuses on delivery performance and does not care about energy efficiency, with three main limitations: 1. Most of these works ignore geographic information along the delivery route, while road slope is one of the most critical energy consumption components. 2. Vehicle and drone power consumption models are simplified as driving mileage, while the delivery time is a significant concern. 3. The battery model is simplified as a linear model even though practical batteries have non-linearity properties. This work proposes a framework to provide energy- and time-efficient delivery schedules with a hybrid delivery service with terrestrial and aerial electric vehicles. We first implement accurate electric van and drone power models and a battery model based on manufacturers' system specifications and experimental data. Then, we propose a heuristic delivery scheduling algorithm to determine the electric van and drone delivery schedule. We also introduce various cost functions to evaluate the delivery scheduling results regarding time, energy, the weighted sum of time and energy, and the economic model. The proposed framework is validated on randomly implemented delivery missions and delivery scenarios in existing cities. Results indicate that the coordinated delivery saves delivery costs up to 27.25% in terms of the economic model compared with the electric van-only delivery schedule